Hot Air Balloons

We wanted to find out how hot air balloons work and if we could make one ourselves. We know that hot air rises and is less dense than cold air, so we searched for some ideas.
This clip showed us how to make a hot air balloon so we basically followed what they did (on a shoe-string budget though!!)

We tried to lift a plastic bag with a hair drier on Wednesday afternoon, but it wouldn't rise. After some thinking, we realised that the classroom was too warm -- so we tried the same thing the following morning when the temperature was cooler. The bag lifting off was a real success.

Next step was to make a large tube that was light enough to lift off the ground. We used very thin computer paper, fine bamboo, tape, and balloons.
A little decoration was added but not too much as paint would have weighed our hot air contraptions down.

Then down to the hall Friday morning to experiment.
Success! They lifted off the ground. The hair drier gave enough wind to lift them off the ground. A bot too much heat though so one balloon popped. (Interesting thing about that though was that the popping balloon caused the paper to rip - the force of the air was that strong!)
Check out the photos!